U.S. patent application number 11/027925 was filed with the patent office on 2006-06-29 for thermoplastic composites with improved sound absorbing capabilities.
Invention is credited to Arthur Blinkhorn, Terry Cheney, Enamul Haque.
Application Number | 20060137799 11/027925 |
Document ID | / |
Family ID | 36118303 |
Filed Date | 2006-06-29 |
United States Patent
Application |
20060137799 |
Kind Code |
A1 |
Haque; Enamul ; et
al. |
June 29, 2006 |
Thermoplastic composites with improved sound absorbing
capabilities
Abstract
A composite material formed of reinforcement fibers, acoustical
enhancing fibers such as polyethylene terephthalate (PET) fibers or
modified polyethylene terephthalate fibers, and one or more organic
fibers is provided. The acoustical enhancing fiber may be any fiber
that provides increased or enhanced acoustical absorbance,
particularly at low frequencies. The composite material may be
formed by partially opening wet reinforcing fibers, acoustical
enhancing fibers, and organic fibers, mixing the reinforcing,
acoustical enhancement, and organic fibers, forming the fibers into
a sheet, and bonding the fibers in the sheet. Preferably the
reinforcing fibers are wet use chopped strand glass fibers. The
composite material may be formed of a single layer of
reinforcement, acoustical enhancement fibers, and organic fibers.
Alternatively, the composite material may be a multi-layered
composite in which the acoustical enhancement fibers are located in
an acoustical layer laminated to a thermal layer formed of the
organic fibers and reinforcement fibers.
Inventors: |
Haque; Enamul; (Novi,
MI) ; Cheney; Terry; (Northville, MI) ;
Blinkhorn; Arthur; (Fenton, MI) |
Correspondence
Address: |
OWENS CORNING
2790 COLUMBUS ROAD
GRANVILLE
OH
43023
US
|
Family ID: |
36118303 |
Appl. No.: |
11/027925 |
Filed: |
December 29, 2004 |
Current U.S.
Class: |
156/62.2 ;
156/182; 156/245 |
Current CPC
Class: |
B32B 2250/40 20130101;
D04H 1/43828 20200501; B32B 2307/31 20130101; D04H 1/43832
20200501; D04H 1/43835 20200501; B32B 5/26 20130101; B32B 5/06
20130101; B32B 2250/20 20130101; B32B 2307/54 20130101; D04H 1/4383
20200501; B32B 2260/023 20130101; B32B 2250/03 20130101; B32B
2307/546 20130101; B32B 7/12 20130101; B32B 2419/04 20130101; B32B
5/08 20130101; D04H 1/48 20130101; D04H 1/485 20130101; B32B
2262/0284 20130101; B32B 2262/12 20130101; B32B 2307/558 20130101;
B32B 2307/304 20130101; D04H 1/435 20130101; B32B 2262/14 20130101;
D04H 1/732 20130101; B32B 2260/048 20130101; B32B 2605/08 20130101;
B60R 13/08 20130101; D04H 1/54 20130101; B32B 2260/046 20130101;
B32B 2262/101 20130101; B32B 2307/102 20130101 |
Class at
Publication: |
156/062.2 ;
156/182; 156/245 |
International
Class: |
B27N 3/00 20060101
B27N003/00; B32B 37/00 20060101 B32B037/00 |
Claims
1. A method of making an acoustic and thermally absorbent composite
material comprising the steps of: at least partially opening bales
of wet reinforcing fibers; removing water from said at least
partially opened wet reinforcing fibers to form dehydrated
reinforcing fibers; blending said dehydrated reinforcing fibers
with organic fibers and acoustical enhancement fibers to form a
substantially homogenous mixture of said dehydrated reinforcing
fibers, said organic fibers, and said acoustical enhancement
fibers; forming said mixture into a sheet; and bonding at least
some of said dehydrated reinforcing fibers, said organic fibers,
and said acoustical enhancement fibers to form a composite
material.
2. The method of claim 1, wherein said bonding step comprises:
subjecting said sheet to a needling process to mechanically bond
said dehydrated reinforcing fibers, said organic fibers, and said
acoustical enhancement fibers.
3. The method of claim 1, wherein said bonding step comprises:
heating said sheet to a temperature above the melting point of at
least one of said organic fibers and said acoustical enhancement
fibers and below the melting point of said dehydrated reinforcing
fibers to at least partially melt at least one of said organic
fibers and said acoustical enhancement fibers.
4. The method of claim 1, further comprising the step of: adding a
bonding agent prior to said bonding step, said bonding agent being
selected from the group consisting of resin powders, resin flakes,
latex polymers, resin granules, adhesive foams and organic
solvents.
5. The method of claim 1, wherein said forming step comprises:
passing said mixture through at least one sheet former.
6. The method of claim 5, further comprising the step of:
transporting said mixture to a filling box tower prior to said
forming step, said filling box tower volumetrically feeding said
mixture to said sheet former.
7. The method of claim 1, wherein said organic fibers are selected
from the group consisting of bicomponent fibers, polyester fibers,
polyethylene fibers, polypropylene fibers, polyethylene
terephthalate (PET) fibers, polyphenylene sulfide (PPS) fibers,
polyvinyl chloride (PVC) fibers, ethylene vinyl acetate/vinyl
chloride (EVA/VC) fibers, lower alkyl acrylate polymer fibers,
acrylonitrile polymer fibers, partially hydrolyzed polyvinyl
acetate fibers, polyvinyl alcohol fibers, polyvinyl pyrrolidone
fibers, styrene acrylate fibers, polyolefins, polyamides,
polysulfides, polycarbonates, rayon, nylon and butadiene
copolymers.
8. The method of claim 7, wherein said acoustical enhancement
fibers are selected from the group consisting of polyethylene
terephthalate (PET) fibers and modified polyethylene terephthalate
fibers.
9. The method of claim 8, wherein said wet reinforcing fibers are
wet use chopped strand glass fibers.
10. A composite mat made by the method of claim 1.
11. A method of forming a laminate composite product comprising the
steps of: forming a first layered material including: depositing a
first adhesive layer formed of a first adhesive onto a first scrim;
positioning a layer of a first composite material on said first
adhesive layer, said composite material including dehydrated wet
reinforcing fibers, organic fibers, and acoustical enhancement
fibers; placing a second adhesive layer formed of a second adhesive
on said first composite material layer; forming a second layered
material including: depositing a third adhesive layer formed of a
third adhesive onto a core layer, said core layer being formed of a
member selected from the group consisting of polyethylene
terephthalate fibers, modified polyethylene terephthalate fibers
and combinations thereof; placing a layer of a second composite
material including said reinforcing fibers, said acoustical
enhancement fibers, and said organic fibers on said third adhesive
layer; and depositing a fourth adhesive layer formed of a fourth
adhesive onto said second composite material layer; and positioning
said second layered material and said first layered material such
that said second adhesive layer is located adjacent to said core
layer to form a laminate composite product.
12. The method of claim 11, wherein said laminate composite product
is a headliner for an automobile and said method further comprises
the steps of: trimming said laminate composite product; and molding
said trimmed laminate composite product into a headliner.
13. The method of claim 12, further comprising the step of: heating
said laminate composite product prior to said trimming step.
14. The method of claim 11, further comprising the step of forming
said composite material, said forming step comprising: at least
partially opening bales of wet reinforcing fibers; removing water
from said at least partially opened wet reinforcing fibers to form
dehydrated reinforcing fibers; blending said dehydrated reinforcing
fibers with organic fibers and acoustical enhancement fibers to
form a substantially homogenous mixture of said dehydrated
reinforcing fibers, said organic fibers, and said acoustical
enhancement fibers; forming said mixture into a sheet; and bonding
at least some of said dehydrated reinforcing fibers, said organic
fibers, and said acoustical enhancement fibers to form said
composite material.
15. The method of claim 11, wherein said first, second, third, and
fourth adhesives have a form selected from the group consisting of
a liquid form, a foam form and a powdered form.
16. A method of making a composite material comprising the steps
of: at least partially opening bales of wet reinforcing fibers;
removing water from said at least partially opened wet reinforcing
fibers to form dehydrated reinforcing fibers; blending said
dehydrated reinforcing fibers with organic fibers to form a
substantially homogenous mixture of said dehydrated reinforcing
fibers and said organic fibers; forming said mixture into a sheet;
bonding said reinforcing fibers and organic fibers in said sheet to
form a first layer; and affixing a second layer formed of
acoustical enhancement fibers to said first layer to form a
composite material, said acoustical enhancement fibers being
selected from the group consisting of polyethylene terephthalate
fibers and modified polyethylene terephthalate fibers.
17. The method of claim 16, wherein said organic fibers are
selected from the group consisting of bicomponent fibers, polyester
fibers, polyethylene fibers, polypropylene fibers, polyethylene
terephthalate (PET) fibers, polyphenylene sulfide (PPS) fibers,
polyvinyl chloride (PVC) fibers, ethylene vinyl acetate/vinyl
chloride (EVA/VC) fibers, lower alkyl acrylate polymer fibers,
acrylonitrile polymer fibers, partially hydrolyzed polyvinyl
acetate fibers, polyvinyl alcohol fibers, polyvinyl pyrrolidone
fibers, styrene acrylate fibers, polyolefins, polyamides,
polysulfides, polycarbonates, rayon, nylon and butadiene
copolymers.
18. The method of claim 17, wherein said wet reinforcing fibers are
wet use chopped strand glass fibers.
19. The method of claim 16, wherein said bonding step comprises:
heating said sheet to a temperature above the melting point of said
organic fibers and below the melting point of said dehydrated
reinforcing fibers to at least partially melt said organic fibers
and bond at least a portion of said dehydrated reinforcing fibers
and said organic fibers.
20. The method of claim 19, further comprising the step of:
subjecting said sheet to a needling process to mechanically bond
said dehydrated reinforcing fibers and said organic fibers prior to
said bonding step.
21. The method of claim 15, further comprising the step of: adding
a bonding agent prior to said bonding step, said bonding agent
being selected from the group consisting of resin powders, resin
flakes, latex polymers, resin granules, adhesive foams and organic
solvents.
Description
[0001] TECHNICAL FIELD AND INDUSTRIAL APPLICABILITY OF THE
INVENTION
[0002] The present invention relates generally to acoustical
products, and more particularly, to a composite material that
includes reinforcement fibers, organic fibers, and polyethylene
terephthalate (PET) fibers and which possesses improved sound
absorption at lower frequencies. A method of forming the composite
material is also provided.
BACKGROUND OF THE INVENTION
[0003] Sound insulation materials are used in a variety of settings
where it is desired to dampen noise from an external source. For
example, sound insulation materials have been used in applications
such as in appliances to reduce the sound emitted into the
surrounding areas of a home, in automobiles to reduce mechanical
sounds of the motor and road noise, and in office buildings to
attenuate sound generated from the workplace, such as from
telephone conversations or from the operation of office equipment.
Conventional acoustical insulation materials include materials such
as foams, compressed fibers, fiberglass batts, felts, and nonwoven
webs of fibers such as meltblown fibers. Acoustical insulation
typically relies upon both sound absorption (the ability to absorb
incident sound waves) and transmission loss (the ability to reflect
incident sound waves) to provide adequate sound attenuation.
[0004] In automobiles, the insulation material also relies upon
thermal shielding properties to reduce or prevent the transmission
of heat from various heat sources in the automobile (engine,
transmission, exhaust, etc.) to the passenger compartment of the
vehicle. Such insulation is commonly employed in the automobile as
a headliner, dash liner, or firewall liner. Liners are typically
formed of laminates of one or more layers of an insulation material
to provide desired mechanical strength properties and one or more
additional layers of a rigid material to permit simple and
convenient installation in the automobile as well as proper
functional performance. Examples of conventional acoustical
insulation materials are set forth below.
[0005] U.S. Pat. No. 4,889,764 to Chenoweth et al. and U.S. Pat.
No. 4,946,738 describe a non-woven fibrous blanket that includes
mineral fibers (glass fibers), synthetic fibers (polyester), and
bi-component fibers. The synthetic fibers preferably have lengths
of from 1/4 to 4 inches and a deniers ranging from 1-15 denier. The
bicomponent fibers preferably have lengths from 1/4-3 inches and
deniers ranging from 1-10 denier.
[0006] U.S. Pat. No. 5,591,289 to Souders et al. discloses a
headliner that has a fibrous core formed from a high loft batting
of polymeric thermoplastic fibers (polypropylene and polyethylene
terephthalate). The fibers have a length of approximately 2 inches
and a denier in the range of from 5-30.
[0007] U.S. Pat. No. 5,662,981 to Olinger et al. describes a molded
composite product that has a resinous core layer that contains
reinforcement fibers (glass and polymer fibers) and a resinous
surface layer that is substantially free of reinforcement fibers.
The surface layer may be formed of thermoplastics or thermoset
materials such as poytretrafluoroethylene, polyethylene
terephthalate (PET), polyvinyl chloride (PVC), polyphenylene
sulfide (PPS), or polycarbonate.
[0008] U.S. Pat. No. 5,886,306 to Patel et al. discloses a layered
acoustical insulating web that includes a series of cellulose fiber
layers sandwiched between a layer of melt-blown or spun-bond
thermoplastic fibers (polypropylene) and a layer of film, foil,
paper, or spunbond thermoplastic fibers.
[0009] U.S. Pat. No. 6,669,265 to Tilton et al. describes a fibrous
material that has a lofty, acoustically insulating portion and a
relatively higher density skin that may function as a water
barrier. The fibrous material includes polyester, polyethylene,
polypropylene, polyethylene terephthalate (PET), glass fibers,
natural fibers, and mixtures thereof.
[0010] U.S. Pat. No. 6,695,939 to Nakamura et al. discloses an
interior trim material that is formed of a substrate and a skin
bonded to the substrate. The substrate is a mat-like fiber
structure that is a blend of thermoplastic and inorganic fibers.
The skin is a high melting point fiber sheet formed from fibers
that have a melting point higher than the melting point of the
thermoplastic fibers in the substrate. The high melting point
fibers may be polyethylene terephthalate (PET) fibers.
[0011] U.S. Pat. No. 6,756,332 to Sandoe et al. describes a
headliner that includes a core layer formed from a batt of blended
non-woven fibers between two stiffening layers. The core layer
includes thermoplastic fibers having (1) 20-50% fine fibers by
weight with a denier in the range of 0.8-3.0, (2) 10-50% binder
fibers by weight, and (3) other fibers with deniers in the range of
4.0-15.0. The thermoplastic fibers can include polyester,
polyolefin, and nylon. The polyester fibers preferably include
bicomponent fibers.
[0012] U.S. Patent Publication No. 2003/0039793 A1 to Tilton et al.
describes a trim panel insulator for a vehicle that includes a
nonlaminate acoustical and thermal insulating layer of polymer
fibers. The insulator may also include a relatively high density,
nonlaminate skin of polymer fibers and/or one or more facing layers
formed of polyester, polypropylene, polyethylene, rayon, ethylene
vinyl acetate, polyvinyl chloride, fibrous scrim, metallic foil,
and mixtures thereof.
[0013] U.S. Patent Publication No. 2004/0002274 A1 to Tilton
discloses a laminate material that includes (1) a base layer formed
of polyester, polypropylene, polyethylene, fiberglass, natural
fibers, nylon, rayon, and blends thereof and (2) a facing layer.
The base layer has a density of from approximately 0.5-15.0 pcf and
the facing layer has a density of between about 10 pcf and about
100 pcf.
[0014] U.S. Patent Publication No. 2004/0023586 A1 to Tilton et al.
and U.S. Patent Publication No. 2003/0008592 to Block et al.
disclose a fibrous blanket material that has a first fibrous layer
formed of polyester, polypropylene, polyethylene, fiberglass,
natural fibers, nylon, and/or rayon and a layer of meltblown
polypropylene fibers. A second fibrous layer may be sandwiched
between the first fibrous layer and the layer of meltblown fibers.
The blanket material may be tuned to provide sound attenuation for
a particular product application.
[0015] U.S. Patent Publication No. 2004/0077247 to Schmidt et al.
describes a nonwoven laminate that contains a first layer formed of
thermoplastic spunbond filaments having an average denier less than
about 1.8 dpf and a second layer containing thermoplastic
multicomponent spunbond filaments having an average denier greater
than about 2.3 dpf. The laminate has a structure such that the
density of the first layer is greater than the density of the
second layer and the thickness of the second layer is greater than
the thickness of the first layer.
[0016] Although there are numerous acoustical insulation products
in existence in the art for automotive applications, none of the
existing insulation products provide sufficient sound absorption at
low frequencies while maintaining sufficient structural properties.
Thus, there exists a need for acoustical materials that exhibit
superior sound attenuating properties, improved structural and
thermal properties, and that are lightweight and low in cost.
SUMMARY OF THE INVENTION
[0017] It is an object of the present invention to provide a method
for making an acoustic and thermally absorbent composite material
that includes reinforcing fibers, organic fibers, and acoustical
enhancement fibers. To form the composite material, wet
reinforcement fibers are opened and filamentized and at least a
portion of the water present in the wet reinforcement fibers is
removed to form dehydrated reinforcement fibers. The dehydrated
reinforcement fibers are blended with acoustical enhancement fibers
and organic fibers, such as in a high velocity air stream, to form
a substantially homogenous mixture of the fibers. The mixture is
then transferred to a sheet former and formed into a sheet. At
least some of the dehydrated reinforcement fibers, organic fibers,
and acoustical enhancement fibers are bonded to form a composite
material. In at least one exemplary embodiment, the sheet is heated
to a temperature above the melting point of the organic fibers
and/or acoustical enhancement fibers and below the melting point of
the dehydrated reinforcing fibers to at least partially melt the
organic fibers and/or acoustical enhancement fibers and bond the
reinforcement, organic, and acoustical enhancement fibers together.
In a preferred embodiment, the reinforcement fibers are wet use
chopped strand glass fibers. The acoustical enhancement fibers are
preferably polyethylene terephthalate fibers and/or modified
polyethylene terephthalate fibers.
[0018] It is another object of the present invention to provide a
method of forming a laminate composite product. In a first assembly
line, a first layered material that includes sequential layers of a
scrim, a first adhesive, a composite material that includes
reinforcing fibers, acoustical enhancement fibers, and organic
fibers, and a second adhesive is formed. In a second assembly line,
a second layered material formed of a core layer of polyethylene
terephthalate fibers and/or modified polyethylene terephthalate
fibers, a third adhesive layer, a composite material that includes
reinforcing fibers, acoustical enhancement fibers, and organic
fibers, and a fourth adhesive layer is produced. The first and
second assembly lines may converge in-line such that the second
adhesive layer is positioned adjacent to the polyethylene
terephthalate fiber core layer. The layered composite thus formed
may be passed through a lamination oven where heat and pressure are
applied to form a laminated composite material. The laminated
composite material may be further processed by conventional methods
into composite products such as a liner for an automobile. For
example, the laminated composite material may be trimmed and formed
into a headliner, such as by a molding process. Foam or fabric may
then be applied to the headliner for aesthetic purposes.
[0019] It is yet another object of the present invention to provide
a method of making a composite material that is formed of (1) a
first layer that includes reinforcing fibers and organic fibers and
(2) a second layer that includes acoustical enhancement fibers. To
form the first layer, bales of wet reinforcing reinforcement fibers
are opened and filamentized and at least a portion of the water
present in the wet reinforcing fibers is removed to form dehydrated
reinforcing fibers. The dehydrated reinforcing fibers are mixed
with organic fibers to form a substantially homogenous mixture of
fibers. The mixture is then transferred to a sheet former and
formed into a sheet. At least some of the dehydrated reinforcement
fibers and organic fibers are bonded to form the first layer. In at
least one exemplary embodiment, the sheet is heated to a
temperature above the melting point of the organic fibers and below
the melting point of the dehydrated reinforcing fibers to at least
partially melt the organic fibers and bond the reinforcing and
organic fibers together. In a preferred embodiment, the
reinforcement fibers are wet use chopped strand glass fibers. A
second layer of acoustical enhancement fibers is positioned on the
first layer to form the composite product. It is preferred that the
acoustical enhancement fibers are polyethylene terephthalate fibers
and/or modified polyethylene terephthalate fibers. In addition, the
second layer may be formed by an air-laid, wet-laid, or meltblown
process. The second layer may optionally include heat fusible
fibers such as bicomponent fibers. The acoustical behavior of the
composite product may be fine tuned by altering the lengths and
denier of the acoustical enhancement fibers.
[0020] It is an advantage of the present invention that the
acoustic performance of the composite material may be altered or
improved by the specific combination of fibers present in the
composite material, and can therefore be tailored to meet the needs
of a particular application. For example, the acoustic properties
desired for specific applications can be optimized by altering the
weight of the fibers, by changing the reinforcement fibers content
and/or length or diameter of the reinforcement fibers, or by
altering the fiber length and/or denier of the acoustical enhancing
fibers or organic fibers.
[0021] It is another advantage of the present invention that the
thickness of composite parts formed from the composite material,
the porosity of the formed composite parts (void content), and the
air flow path of the formed composite parts may be controlled by
changing the basis weight of the organic fibers and/or
reinforcement fiber content of the composite material.
[0022] It is a further advantage that the composite material formed
in a dry-laid process that uses wet use chopped strand glass such
as in the present invention has a higher loft (increased
porosity).
[0023] It is yet another advantage of the present invention that
the composite material provides the ability to optimize and/or
tailor the physical properties needed for specific applications
(such as stiffness or strength) by altering the weight, length,
and/or denier of the reinforcement fibers and/or organic fibers
used in the composite material.
[0024] It is a further advantage of the present invention that
composite materials formed by the processes described herein have a
uniform or substantially uniform distribution of fibers, thereby
providing improved strength as well as improved acoustical and
thermal properties, strength, stiffness, impact resistance, and
acoustical absorbance.
[0025] It is another advantage of the present invention that when
wet use chopped strand glass fibers are used as the reinforcing
fiber material, the glass fibers may be easily opened and fiberized
with little generation of static electricity due to the moisture
present in the glass fibers.
[0026] It is also an advantage of the present invention that the
final product formed can be manufactured at lower costs because wet
use chopped strand glass fibers are less expensive to manufacture
than dry chopped fibers (dry fibers are typically dried and
packaged in separate steps before being chopped).
[0027] The foregoing and other objects, features, and advantages of
the invention will appear more fully hereinafter from a
consideration of the detailed description that follows. It is to be
expressly understood, however, that the drawings are for
illustrative purposes and are not to be construed as defining the
limits of the invention.
BRIEF DESCRIPTION OF THE DRAWINGS
[0028] The advantages of this invention will be apparent upon
consideration of the following detailed disclosure of the
invention, especially when taken in conjunction with the
accompanying drawings wherein:
[0029] FIG. 1 is a flow diagram illustrating steps for using wet
reinforcement fibers in a dry-laid process according to one aspect
of the present invention;
[0030] FIG. 2 is a schematic illustration an air-laid process using
wet reinforcement fibers to form a composite material according to
at least one exemplary embodiment of the present invention;
[0031] FIG. 3 is a schematic illustration of a composite material
formed of an acoustical layer and a thermal layer according to at
least one exemplary embodiment of the present invention;
[0032] FIG. 4 is a schematic illustration of an air-laid process
utilizing acoustical enhancement fibers and polymeric fibers to
form an acoustical layer according to at least one exemplary
embodiment of the present invention;
[0033] FIG. 5 is a schematic illustration of a laminate process for
making a layered composite product according to at least one
exemplary embodiment of the present invention;
[0034] FIG. 6 is a schematic illustration of the layered composite
product formed by the exemplary process depicted in FIG. 5;
[0035] FIG. 7 is a graphical illustration of the random incident
sound absorption of a conventional polypropylene/glass composite
material and a polypropylene/glass/polyethylene terephthalate
composite material according to the present invention; and
[0036] FIG. 8 is a graphical illustration of the normal incident
sound absorption of a conventional polypropylene/glass composite
material and a polyethylene terephthalate/glass composite material
according the present invention.
DETAILED DESCRIPTION AND PREFERRED EMBODIMENTS OF THE INVENTION
[0037] Unless defined otherwise, all technical and scientific terms
used herein have the same meaning as commonly understood by one of
ordinary skill in the art to which the invention belongs. Although
any methods and materials similar or equivalent to those described
herein can be used in the practice or testing of the present
invention, the preferred methods and materials are described
herein. All references cited herein, including published or
corresponding U.S. or foreign patent applications, issued U.S. or
foreign patents, or any other references, are each incorporated by
reference in their entireties, including all data, tables, figures,
and text presented in the cited references.
[0038] In the drawings, the thickness of the lines, layers, and
regions may be exaggerated for clarity. It is to be noted that like
numbers found throughout the figures denote like elements. The
terms "top", "bottom", "side", and the like are used herein for the
purpose of explanation only. It will be understood that when an
element such as a layer, region, substrate, or panel is referred to
as being "on" another element, it can be directly on the other
element or intervening elements may be present. If an element or
layer is described as being "adjacent to" or "against" another
element or layer, it is to be appreciated that the element or layer
may be directly adjacent or directly against that other element or
layer, or intervening elements may be present. It will also be
understood that when an element such as a layer, region, or
substrate is referred to as being "over" another element, it can be
directly over the other element, or intervening elements may be
present. The terms "reinforcing fibers" and "reinforcement fibers"
may be use interchangeably herein. Further, the term "acoustical
enhancement fibers" may be used interchangeably with the term
"acoustical enhancing fibers".
[0039] The present invention relates to an acoustic and thermally
absorbent composite material that is formed of reinforcement
fibers, acoustical enhancing fibers such as polyethylene
terephthalate (PET) fibers or modified polyethylene terephthalate
fibers, and one or more organic fibers. The composite material may
be utilized in numerous structural applications such as in
automobiles (head liners, hood liners, floor liners, trim panels,
parcel shelves, vehicle sunshades, instrument panel structures,
door inners, and the like), and in wall panels and roof panels of
recreational vehicles (RV's) as well as in a number of
non-structural acoustical applications such as in kitchen
appliances, in office screens and partitions, in ceiling tiles, in
building panels, and in basement finishing systems.
[0040] The reinforcement fibers utilized in the composite material
may be any type of organic or inorganic fiber suitable for
providing good structural qualities as well as good acoustical and
thermal properties. Non-limiting examples of reinforcement fibers
that may be utilized in the composite material include glass
fibers, wool glass fibers, natural fibers, metal fibers, ceramic
fibers, mineral fibers, carbon fibers, graphite fibers, nanofibers,
and combinations thereof. The term "natural fiber" as used in
conjunction with the present invention refers to plant fibers
extracted from any part of a plant, including, but not limited to,
the stem, seeds, leaves, roots, or bast. In the composite material,
the reinforcement fibers may have the same or different lengths,
diameters, and/or denier. Preferably, the reinforcing fiber
material is glass fibers.
[0041] The reinforcement fibers utilized in the composite material
may have a length of from approximately 10-100 mm in length, and
even more preferably, a length of from 25-50 mm. Additionally, the
reinforcing fibers may have diameters of from 11-25 microns, and
preferably have diameters of from 12-18 microns. The reinforcing
fibers may have varying lengths (aspect ratios) and diameters from
each other within the composite material. The reinforcing fibers
may be present in the composite material in an amount of from
20-60% by weight of the total fibers, and are preferably present in
the composite material in an amount of from 30-50% by weight.
[0042] In addition, the composite material includes at least one
acoustical enhancing fiber. The acoustical enhancing fiber may be
any fiber that provides increased or enhanced acoustical
absorbance, particularly at lower frequencies, such as, for
example, frequencies below approximately 2000 Hz. Non-limiting
examples of such fibers include polyethylene terephthalate (PET)
fibers and modified polyethylene terephthalate fibers (such as poly
1,4 cyclohexanedimethyl terephthalate, glycol modified polyethylene
terephthalate), cotton and jute fibers (cellulosic and natural),
glass fibers, and polyurethane foam. Preferably, the acoustical
enhancement fibers are polyethylene terephthalate fibers or
modified polyethylene terephthalate fibers. The acoustical
enhancing fibers may have different denier and fiber lengths to
provide increased sound absorption. The acoustical enhancing fibers
utilized in the composite material may have a length of from
approximately 6-75 mm in length, and preferably have a length of
from 18-50 mm. In addition, the acoustical enhancing fibers may
have a denier from approximately 1.5-30 denier, preferably from
1.5-6 denier. The acoustical enhancing fibers may present in the
composite material in an amount of from 30-70% by weight of the
total fibers, and are preferably present in an amount of from
30-40% by weight.
[0043] Additionally, the composite material includes at least one
organic fiber. The organic fibers present in the composite material
may include polymer based thermoplastic fibers such as, but not
limited to, polyester fibers, polyethylene fibers, polypropylene
fibers, polyethylene terephthalate (PET) fibers, polyphenylene
sulfide (PPS) fibers, polyvinyl chloride (PVC) fibers, ethylene
vinyl acetate/vinyl chloride (EVA/VC) fibers, lower alkyl acrylate
polymer fibers, acrylonitrile polymer fibers, partially hydrolyzed
polyvinyl acetate fibers, polyvinyl alcohol fibers, polyvinyl
pyrrolidone fibers, styrene acrylate fibers, polyolefins,
polyamides, polysulfides, polycarbonates, rayon, nylon and
butadiene copolymers such as styrene/butadiene rubber (SBR) and
butadiene/acrylonitrile rubber (NBR). The organic fibers may be
functionalized with acidic groups, for example, by carboxylating
with an acid such as a maleated acid or an acrylic acid, or the
polymer fibers may be functionalized by adding an anhydride group
or vinyl acetate. The organic fibers may alternatively be in the
form of a flake, granule, or a powder rather than in the form of a
polymer fiber. In some embodiments, a resin in the form of a flake,
granule, and/or a powder is added in addition to the organic
fibers.
[0044] One or more types of organic fibers may be present in the
composite material. The specific combination of the types of
organic fibers present in the composite material will vary to meet
the specific acoustical requirements of a particular application.
The organic fibers present in the composite material may have the
same or different lengths, diameters, and/or denier. For example,
the organic fibers of the composite material may include a single
polymeric fibrous material (such as polypropylene) in which the
polymer fibers have different lengths, diameters, and/or denier. As
another example, the organic fibers present in the composite
material may include two or more different polymeric fibrous
materials, and each of the polymers may have the same lengths
and/or diameters and/or denier, or, alternatively, the polymers may
have different lengths and/or diameters and/or denier. The
acoustical behavior of the composite material may be fine tuned by
altering the lengths and denier of the organic polymer fibers. In
addition, the ratio of the different organic fibers present in the
composite material can be varied to achieve specific acoustic
properties.
[0045] The organic fibers may have a length of from approximately
6-75 mm, and preferably have a length of from 18-50 mm.
Additionally, the organic fibers may have a denier of from 2-30
denier, preferably from 2-18 denier, and more preferably, from 3-7
denier. The organic fibers present in the composite material may
have varying lengths and diameters, depending on the desired
acoustical characteristics of the composite material. The polymer
fibers may be present in the composite material in an amount of
from 10-50% by weight of the total fibers, and are preferably
present in an amount of from 10-30% by weight.
[0046] One or more of the organic fibers may be a multicomponent
fibers such as bicomponent polymer fibers, tricomponent fibers, or
plastic-coated mineral fibers such as thermoplastic coated glass
fibers. The bicomponent fibers may be arranged in a sheath-core,
side-by-side, islands-in-the-sea, or segmented-pie arrangement.
Preferably, the bicomponent fibers are formed in a sheath-core
arrangement in which the sheath is formed of first polymer fibers
which substantially surround the core formed of second polymer
fibers. It is not required that the sheath fibers totally surround
the core fibers. The first polymer fibers have a melting point
lower than the melting point of the second polymer fibers so that
upon heating the bicomponent fibers, the first and second polymer
fibers react differently. In particular, when the bicomponent
fibers are heated to a temperature that is above the melting point
of the first polymer fibers (sheath fibers) and below the melting
point of the second polymer fibers (core fibers), the first polymer
fibers will soften or melt while the second polymer fibers remain
intact. This softening of the first polymer fibers (sheath fibers)
will cause the first polymer fibers to become sticky and bond the
first polymer fibers to themselves and other fibers that may be in
close proximity.
[0047] Numerous combinations of materials can be used to make the
bicomponent polymer fibers, such as, but not limited to,
combinations using polyester, polypropylene, polysulfide,
polyolefin, and polyethylene fibers. Specific polymer combinations
for the bicomponent fibers include polyethylene
terephthalate/polypropylene, polyethylene
terephthalate/polyethylene, and polypropylene/polyethylene. Other
non-limiting bicomponent fiber examples include copolyester
polyethylene terephthalate/polyethylene terephthalate (coPET/PET),
poly 1,4 cyclohexanedimethyl terephthalate/polypropylene (PCT/PP),
high density polyethylene/polyethylene terephthalate (HDPE/PET),
high density polyethylene/polypropylene (HDPE/PP), linear low
density polyethylene/polyethylene terephthalate (LLDPE/PET), nylon
6/nylon 6,6 (PA6/PA6,6), and glycol modified polyethylene
terephthalate/polyethylene terephthalate (6PETg/PET).
[0048] The bicomponent polymer fibers may have a length of from 2-4
mm and a denier in the range of approximately 1-18 denier. It is
preferred that the first polymer fibers (sheath fibers) have a
melting point within the range of from about 150-400.degree. F.,
and more preferably in the range of from about 170-300.degree. F.
The second polymer fibers (core fibers) have a higher melting
point, preferably above about 350.degree. F. When bicomponent
fibers are used as a component of the composite material, the
bicomponent fibers may be present in an amount up to 20% by weight
of the total fibers, preferably in an amount up to 10% by
weight.
[0049] The composite material may be formed of an air-laid,
wet-laid, or meltblown non-woven mat or web of randomly oriented
reinforcement fibers, acoustical enhancing fibers, and/or organic
fibers. In at least one exemplary embodiment, the composite
material is formed by a dry-laid process, such as the dry-laid
process described in U.S. patent application Ser. No. 10/688,013,
filed on Oct. 17, 2003, to Enamul Haque entitled "Development Of
Thermoplastic Composites Using Wet Use Chopped Strand Glass In A
Dry Laid Process", incorporated herein by reference in its
entirety. In preferred embodiments, the reinforcing fibers used to
form the composite material are wet reinforcing fibers, and most
preferably are wet use chopped strand glass fibers. Wet use chopped
strand glass fibers for use as the reinforcement fibers may be
formed by conventional processes known in the art. It is desirable
that the wet use chopped strand glass fibers have a moisture
content of from 5-30%, and more preferably have a moisture content
of from 5-15%.
[0050] An exemplary process for forming a composite material in
accordance with the instant invention is generally illustrated in
FIG. 1, and includes at least partially opening the reinforcement
fibers, the acoustical enhancing fibers, and the organic fibers
(step 100), blending the reinforcement, acoustical enhancing
fibers, and organic fibers (step 110), forming the reinforcement,
acoustical enhancing, and organic fibers into a sheet (step 120),
optionally needling the sheet to give the sheet structural
integrity (step 130), and bonding the reinforcement, acoustical
enhancing, and organic fibers (step 140).
[0051] The reinforcing fibers, acoustical enhancement fibers, and
the organic fibers are typically agglomerated in the form of a bale
of individual fibers. In forming the composite material, bales of
reinforcing fibers, acoustical enhancing fibers, and organic fibers
may each be opened by an opening system, such as a bale opening
system, which is common in the industry.
[0052] Turning now to FIG. 2, the opening of the wet reinforcement
fibers, acoustical enhancement fibers, and the organic fibers can
best be seen. Wet reinforcing fibers 200, acoustical enhancement
fibers 210, and organic fibers 220, typically in the form of bales,
are fed into a first opening system 230, a second opening system
240, and a third opening system 250 respectively to at least
partially open and/or filamentize (individualize) the wet
reinforcing fibers 200, acoustical enhancement fibers 210, and
organic fibers 220. It is to be noted that although the exemplary
process depicted in FIGS. 1 and 2 show opening the acoustical
enhancement fibers 210 by a second opening system 240 and opening
the organic fibers 220 by a third opening system 250, the
acoustical enhancement fibers 210 and/or the organic fibers 220 may
be fed directly into the fiber transfer system 270 (embodiment not
illustrated) if the acoustical enhancement fibers 210 and/or
organic fibers 220 are present or obtained in a filamentized form,
and not in the form of a bale. Such embodiments are considered to
be within the purview of this invention.
[0053] In alternate embodiments where the organic fibers are in the
form of a flake, granule, or powder, the third opening system 250
may be replaced with an apparatus suitable for distributing the
flakes, powders, or granules to the fiber transfer system 270 so
that these resinous materials may be mixed with the reinforcement
fibers 200 and acoustical enhancement fibers 210. A suitable
distribution apparatus would be easily identified by those of skill
in the art. In embodiments where a resin in the form of a flake,
granule, or powder is used in addition to the organic fibers 220
(and not in place of), the apparatus distributing the flakes,
granules, or powder may not replace the third opening system
250.
[0054] The first, second, and third opening systems 230, 240, 250
are preferably bale openers, but may be any type of opener suitable
for opening the bales of reinforcing fibers 200, acoustical
enhancement fibers 210, and organic fibers 220. The design of the
openers depends on the type and physical characteristics of the
fiber being opened. Suitable openers for use in the present
invention include any conventional standard type bale openers with
or without a weighing device. The weighing device serves to
continuously weigh the partially opened fibers as they are passed
through the bale opener to monitor the amount of fibers that are
passed onto the next processing step. The bale openers may be
equipped with various fine openers, one or more licker-in drums or
saw-tooth drums, feeding rollers, and/or or a combination of a
feeding roller and a nose bar.
[0055] The partially opened wet reinforcement fibers 200 may then
be dosed or fed from the first opening system 230 to a condensing
unit 260 to remove water from the wet fibers. In exemplary
embodiments, greater than 70% of the free water (water that is
external to the reinforcement fibers) is removed. Preferably,
however, substantially all of the water is removed by the
condensing unit 260. It should be noted that the phrase
"substantially all of the water" as it is used herein is meant to
denote that all or nearly all of the free water is removed. The
condensing unit 260 may be any known drying or water removal device
known in the art, such as, but not limited to, an air dryer, an
oven, rollers, a suction pump, a heated drum dryer, an infrared
heating source, a hot air blower, or a microwave emitting
source.
[0056] After the reinforcement fibers 200 have passed through the
condensing unit 260, the fibers may be passed through another
opening system, such as a bale opener described above, to further
filamentize and separate the reinforcement fibers 200 (not
shown).
[0057] The reinforcing fibers 200, acoustical enhancement fibers
210, and organic fibers 220 are blended together by the fiber
transfer system 270, preferably in a high velocity air stream. The
fiber transfer system 270 serves both as a conduit to transport the
reinforcing fibers 200, acoustical enhancement fibers 210, and
organic fibers 220 to the sheet former 270 and to substantially
uniformly mix the fibers in the air stream. It is desirable to
distribute the reinforcing fibers 200, acoustical enhancement
fibers 210, and organic fibers 220 as uniformly as possible. The
ratio of reinforcing fibers 200, acoustical enhancement fibers 210,
and organic fibers 220 entering the air stream in the fiber
transfer system 270 may be controlled by the weighing device
described above with respect to the first, second, and third
opening systems 230, 240, 250 or by the amount and/or speed at
which the fibers are passed through the opening systems 220, 230,
250. The ratio of reinforcement fibers 200 to acoustical
enhancement fibers 210 to organic fibers 220 may be approximately
50:20:30, reinforcement fibers 200 to acoustical enhancement fibers
210 to organic fibers 220 respectively. However, it is to be
appreciated that the ratio of fibers present within the air stream
will vary depending on the desired structural and acoustical
requirements of the final product.
[0058] Additional fibers such as chopped roving, dry use chopped
strand glass (DUCS), glass fibers, natural fibers (such as jute,
hemp, and kenaf), aramid fibers, metal fibers, ceramic fibers,
mineral fibers, carbon fibers, graphite fibers, polymer fibers, or
combinations thereof may be opened and filamentized by additional
opening systems (not shown) depending on the desired composition of
the composite material. These additional fibers may be added to the
fiber transfer system 270 and mixed with the reinforcing,
acoustical enhancement, and organic fibers 200, 210, 220.
Alternatively, if the fibers are obtained in a filamentized form,
they may be added to the fiber transfer system 270 without first
passing through an opening system. When such additional fibers are
added to the fiber transfer system 270, it is preferred that from
about 10-30% by weight of the total fibers consist of these
additional fibers.
[0059] Turning back to FIG. 2, the mixture of reinforcing fibers
200, acoustical enhancement fibers 210, and organic fibers 220 may
be transferred to a sheet former 280 where the fibers are formed
into a sheet. In at least one exemplary embodiment, the mixture of
fibers is transferred to the sheet former 280 by a high velocity
air stream. In some embodiments of the present invention, the
blended fibers are transported by the fiber transfer system 270 to
a filling box tower 290 where the reinforcing fibers 200,
acoustical enhancement fibers 210, and organic fibers 220 are
volumetrically fed into the sheet former 280, such as by a computer
monitored electronic weighing apparatus, prior to entering the
sheet former 280. The filling box tower 290 is desirably positioned
external to the sheet former 280. The filling box tower 290 may
also include baffles to further blend and mix the reinforcement
fibers 200, acoustical enhancement fibers 210, and organic fibers
220 prior to entering the sheet former 280. In some embodiments,
the sheet former 280 has a condenser and a distribution conveyor to
achieve a higher fiber feed into the filling box tower 290 and to
increase the volume of air through the filling box tower 290. In
order to achieve an improved cross-distribution of the opened
fibers, the distributor conveyor may run transversally to the
direction of the sheet. As a result, the reinforcing fibers 200,
acoustical enhancement fibers 210, and organic fibers 220 may be
transferred into the filling box tower 290 with little or no
pressure and minimal fiber breakage.
[0060] In at least one exemplary embodiment, the sheet formed by
the sheet former 280 is transferred to a second sheet former (not
shown). The second sheet former assists in substantially uniformly
distributing the reinforcement fibers 200, acoustical enhancement
fibers 210, and organic fibers 220 in the sheet. In addition, the
use of an additional sheet former may increase the structural
integrity of the formed sheet. In an alternative embodiment (not
shown), the mixture of reinforcing fibers 200, acoustical
enhancement fibers 210, and organic fibers 220 are blown onto a
drum or series of drums covered with fine wires or teeth to comb
the fibers into parallel arrays prior to entering the sheet former
280 (not shown), as in a carding process.
[0061] The sheet formed by the sheet former 280 contains a
substantially uniform distribution of bundles of reinforcing fibers
210, acoustical enhancement fibers 210, and organic fibers at a
desired ratio and weight distribution. The sheet formed by the
sheet former 270 may have a weight distribution of from 400-3000
g/m.sup.2, with a preferred weight distribution of from about 600
to 2000 g/m.sup.2.
[0062] In one or more embodiments of the invention, the sheet
exiting the sheet former 280 is optionally subjected to a needling
process in a needle felting apparatus 300 in which barbed or forked
needles are pushed in a downward and/or upward motion through the
fibers of the sheet to entangle or intertwine the reinforcing
fibers 200, acoustical enhancement fibers 210, and organic fibers
220 and impart mechanical strength and integrity to the sheet. The
needle felting apparatus 300 may include a web feeding mechanism, a
needle beam with a needleboard, barbed felting needles ranging in
number from about 500 per meter to about 7,500 per meter of machine
width, a stripper plate, a bed plate, and a take-up mechanism.
Mechanical interlocking of the reinforcement fibers 200, acoustical
enhancement fibers 210, and organic fibers 220 is achieved by
passing the barbed felting needles repeatedly into and out of the
sheet. An optimal needle selection for use with the particular
fibers chosen for use in the inventive process would be easily
identified by one of skill in the art.
[0063] Either after the sheet exits the sheet former 280 or after
the optional needling of the sheet, the sheet may be passed through
a thermal bonding system 310 to bond the reinforcement fibers 200,
acoustical enhancement fibers 210, and organic fibers 220 and form
the composite material. However, it is to be appreciated that if
the sheet is needled in the needle felting apparatus 300 and the
reinforcing fibers 200, acoustical enhancement fibers 210, and the
organic fibers 220 are mechanically bonded, the sheet may not need
to be passed through the thermal bonding system 310 to form the
composite material 320.
[0064] In thermal bonding, the thermoplastic properties of the
acoustical enhancement fibers 210 and organic fibers 220 are used
to form bonds with the reinforcement fibers 200 upon heating. In
the thermal bonding system 290, the sheet is heated to a
temperature that is above the melting point of the acoustical
enhancement fibers 210 and/or the organic fibers 220 but below the
melting point of the reinforcement fibers 200. When bicomponent
fibers are used as the organic fibers 220, the temperature in the
thermal bonding system 310 is raised to a temperature that is above
the melting temperature of the sheath fibers, but below the melting
temperature of the reinforcement fibers 200. Heating the acoustical
enhancement fibers 210 and/or the organic fibers 220 to a
temperature above their melting point, or the melting point of the
sheath fibers in the instance where the organic fibers 220 are
bicomponent fibers, causes the acoustical enhancement fibers 210
and/or organic fibers 220 to become adhesive and bond the
acoustical enhancement fibers 210, organic fibers 220, and
reinforcing fibers 200. If the acoustical enhancement fibers 210
and/or organic fibers completely melt, the melted fibers may
encapsulate the reinforcement fibers 200. As long as the
temperature within the thermal bonding system 310 is not raised as
high as the melting point of the reinforcing fibers 200 and/or core
fibers, these fibers will remain in a fibrous form within the
thermal bonding system 310 and composite material 320.
[0065] Although the acoustical enhancement fibers 210 and/or the
organic fibers 220 may be used to bond the reinforcement fibers 200
to each other, a binder resin 285 may be added as an additional
bonding agent prior to passing the sheet through the thermal
bonding system 310. The binder resin 285 may be in the form of a
resin powder, flake, granule, foam, or liquid spray. The binder
resin 285 may be added by any suitable manner, such as, for
example, a flood and extract method or by spraying the binder resin
285 on the sheet. The amount of binder resin 285 added to the sheet
may be varied depending of the desired characteristics of the
composite material. A catalyst such as ammonium chloride,
p-toluene, sulfonic acid, aluminum sulfate, ammonium phosphate, or
zinc nitrate may be used to improve the rate of curing and the
quality of the cured binder resin 285.
[0066] Another process that may be employed to further bond the
reinforcing fibers 200 either alone, or in addition to, the other
bonding methods described herein, is latex bonding. In latex
bonding, polymers formed from monomers such as ethylene (T.sub.g
-125.degree. C.), butadiene (T.sub.g -78.degree. C.), butyl
acrylate (T.sub.g -52.degree. C.), ethyl acrylate (T.sub.g
-22.degree. C.), vinyl acetate (T.sub.g 30.degree. C.), vinyl
chloride (T.sub.g 80.degree. C.), methyl methacrylate (T.sub.g
105.degree. C), styrene (T.sub.g 105 C.), and acrylonitrile
(T.sub.g 130.degree. C.) are used as bonding agents. A lower glass
transition temperature (T.sub.g) results in a softer polymer. Latex
polymers may be added as a spray prior to the sheet entering the
thermal bonding system 310. Once the sheet enters the thermal
bonding system 310, the latex polymers melt and bond the
reinforcement fibers 200 together.
[0067] A further optional bonding process that may be used alone,
or in combination with the other bonding processes described
herein, is chemical bonding. Liquid based bonding agents, powdered
adhesives, foams, and, in some instances, organic solvents can be
used as the chemical bonding agent. Suitable examples of chemical
bonding agents include, but are not limited to, acrylate polymers
and copolymers, styrene-butadiene copolymers, vinyl acetate
ethylene copolymers, and combinations thereof. For example,
polyvinyl acetate (PVA), ethylene vinyl acetate/vinyl chloride
(EVA/VC), lower alkyl acrylate polymers, styrene-butadiene rubber,
acrylonitrile polymer, polyurethane, epoxy resins, polyvinyl
chloride, polyvinylidene chloride, and copolymers of vinylidene
chloride with other monomers, partially hydrolyzed polyvinyl
acetate, polyvinyl alcohol, polyvinyl pyrrolidone, polyester
resins, and styrene acrylate may be used as a chemical bonding
agent. The chemical bonding agent may be applied uniformly by
impregnating, coating, or spraying the sheet.
[0068] The thermal bonding system may include any known heating and
bonding method known in the art, such as oven bonding, oven bonding
using forced air, infrared heating, hot calendaring, belt
calendaring, ultrasonic bonding, microwave heating, and heated
drums. Optionally, two or more of these bonding methods may be used
in combination to bond the fibers in the sheet. The temperature of
the thermal bonding system 310 varies depending on the melting
point of the particular acoustical enhancement fibers 210, organic
fibers 220, binder resins, and/or latex polymers used, and whether
or not bicomponent fibers are present in the sheet.
[0069] In an alternate embodiment (not illustrated), the composite
material is formed by a wet-laid process. For example, reinforcing
fibers, acoustical enhancement fibers, and organic fibers may be
dispersed in an aqueous solution that contains a binder as well as
dispersants, viscosity modifiers, defoaming agents, and/or other
chemical agents and agitated to form a slurry. The reinforcement
fibers, acoustical enhancement fibers, and organic fibers located
in the slurry are then deposited onto a moving screen where water
is removed. Optionally, the mat is dried in an oven. The mat may
then be immersed in a binder composition to impregnate the mat with
the binder composition. The mat is then passed through a curing
oven to remove any remaining water, cure the binder, and at least
partially melt the acoustical enhancement fibers and/or organic
fibers to bind the reinforcing fibers, acoustical enhancement
fibers, and organic fibers together. The resulting composite
material is an assembly of dispersed thermoplastic fibers
(acoustical enhancement fibers and organic fibers) and
reinforcement fibers.
[0070] In the exemplary embodiment illustrated in FIG. 3, the
composite material 320 is formed of an acoustical layer 360 and a
thermal layer 370. In this embodiment, the acoustical enhancement
fibers 210 are located in the acoustical layer 360 affixed or
laminated to the thermal layer 370, which is formed of organic
fibers 220 and reinforcement fibers 200. The thermal layer 370 may
be made by the process described above and depicted in FIGS. 1 and
2 except that the acoustical enhancement fibers are absent. It is
to be understood that the nomenclature for the acoustical layer 360
and the thermal layer 370 are used for ease of discussion herein
and that both the acoustical layer 360 and the thermal layer 370
provide both acoustical and thermal insulating properties.
[0071] The acoustical layer 360 may be a non-woven mat formed by an
air-laid, wet-laid, or meltblown process, and is desirably formed
of 100% of the acoustical enhancing fibers 210 described above.
Alternatively, the acoustical layer 360 may be formed of one or
more acoustical enhancing fibers 210 and a polymer based
thermoplastic organic material such as, but not limited to,
polyester, polyethylene, polypropylene, polyphenylene sulfide
(PPS), polyvinyl chloride (PVC), polyolefins, polyamides,
polysulfides, polycarbonates, and mixtures thereof. Additionally,
the acoustical layer 360 may include heat fusible fibers such as
bicomponent fibers such as are described above. When bicomponent
fibers are used as a component of the acoustical layer 360, they
may be present in an amount of from 10-80% of the total fibers. The
fibers forming the acoustical layer 360 may have the same or
different lengths and/or diameters and/or denier.
[0072] The acoustical layer 360 is positioned on a major surface of
the thermal layer 370, and may be attached to the thermal layer 370
such as by a nip-roll system or by using a laminator. Thus, the
acoustical enhancement fibers 210 are located on one side of the
composite material 320, and are not dispersed throughout the
composite material as described above with respect to FIGS. 1 and
2. Resin tie layers such as Plexar.TM. (commercially available from
Quantum Chemical), Admer.TM. (commercially available from Mitsui
Petrochemical), and Bynel.TM. (an anhydride modified polyolefin
commercially available from DuPont), spray-on adhesives, pressure
sensitive adhesives, ultrasonics, vibration welding, or other
commonly used fixation technologies may be used adhere the
acoustical layer 360 and thermal layer 370.
[0073] The acoustical behavior of the composite product 320 formed
of the thermal layer 370 and the acoustical layer 360 may be fine
tuned by altering the lengths and denier of the acoustical
enhancement fibers 210 and/or the polymer based thermoplastic
organic material (if present) in the acoustical layer 360. In
addition, the ratio of the acoustical enhancement fibers 210 to
other fibrous polymeric materials that may be present in the
acoustical layer 360 can be varied to achieve specific acoustic
properties. In some exemplary embodiments, the length of the
acoustical enhancement fibers 210 in the acoustical layer 360 is
substantially the same length as the reinforcement fibers 200
present in the thermal layer 370 to aid in processing.
[0074] One exemplary embodiment of the formation of an acoustical
layer 360 formed of acoustical enhancing fibers 210 and
thermoplastic based polymer fibers in a dry-laid process is
depicted in FIG. 4. It is to be appreciated that additional
acoustical enhancement fibers and/or polymeric fibers may be used
to form the acoustical layer 360 and that the particular fibers
depicted in FIG. 4 are for illustration only. As shown in FIG. 4,
acoustical enhancement fibers 210 and polymeric fibers 330 may be
opened by passing the acoustical enhancement fibers 210 and the
polymeric fibers 330, typically in the form of a bale, through a
first opener 340 and a second opener 350, respectively, to open and
filamentize the fibers.
[0075] The acoustical enhancement fibers 210 and polymeric fibers
330 may be blended together by the fiber transfer system 270,
preferably in a high velocity air stream. Alternatively, the
acoustical enhancing fibers 210 and the polymeric fibers 330 may be
conveyed to a filling box tower 290 to volumetrically feed the
acoustical enhancement fibers 210 and polymeric fibers 330 to the
sheet former 280. The sheet exiting the sheet former 280 may then
optionally be conveyed to a second sheet former (not shown) and/or
a needle felting apparatus 300 for mechanical strengthening. A
binder resin 285 may be added prior to passing the sheet through
the thermal bonder 310 in a manner such as described above. The
sheet is then passed through a thermal bonder 310 to cure the
binder resin 285 (if present) and bond the acoustical enhancement
fibers 210 and polymeric fibers 330.
[0076] In another exemplary embodiment of the invention, the
composite material is utilized in a laminate process to form a
liner, such as a headliner, for an automobile. An example of such a
laminate process is illustrated in FIG. 5. In a first assembly line
400, a first adhesive layer 410 formed of a first adhesive 420 is
deposited onto a scrim 440 via a dispensing apparatus 430. A
composite material 320 according to the instant invention is fed
from a roll 330 and is laminated onto the first adhesive layer 410.
A second adhesive 450 is deposited onto the composite material 320
to form a second adhesive layer 460. The first layered material
thus produced includes sequential layers of a scrim 440, a first
adhesive layer 410, a layer formed of a composite product 320, and
a second adhesive layer 460.
[0077] In a second assembly line 470, a third adhesive 480 is
deposited via a dispensing apparatus 430 onto a core layer of
polyethylene terephthalate fibers 490 fed from a roll of
polyethylene terephthalate 495. The core layer of polyethylene
terephthalate fibers 490 may be a mat formed entirely of
polyethylene terephthalate fibers, modified polyethylene
terephthalate fibers, or a mixture of polyethylene terephthalate
fibers and modified polyethylene terephthalate fibers. In some
embodiments, other fibers may be included in the core layer 490 to
enhance acoustical absorption at particular frequencies and/or to
act as a barrier for noise at certain frequencies. In preferred
embodiments, only one type of polyethylene terephthalate fiber is
present in the mat. A composite material 320 fed from a roll 330 is
then laminated onto the third adhesive layer 500 and covered by a
fourth adhesive layer 510 such that the composite material 320 is
sandwiched between the third and fourth adhesive layers 500, 510.
The fourth adhesive layer 510 is formed by depositing a third
adhesive 520 from a dispensing apparatus 430. The second layered
material thus produced may be formed of sequential layers of a
polyethylene terephthalate fibers 490, a third adhesive layer 500,
a composite material layer 320, and a fourth adhesive layer
510.
[0078] As depicted in FIG. 5, the first and second assembly lines
may converge in-line in a manner such that the second adhesive
layer 460 is positioned adjacent to the layer of polyethylene
terephthalate 490. The layered composite product 530, shown
schematically in FIG. 6, may be formed of consecutive layers of a
scrim 440, a first adhesive layer 410, a layer of the composite
material 320, a second adhesive layer 460, a polyethylene
terephthalate fiber layer 490, a third adhesive layer 500, a second
layer of composite material 320, and a second adhesive layer 510.
The layered composite product 530 may be passed through a
lamination oven (not shown) where heat and pressure are applied to
form a final laminated composite material (not shown). The
laminated composite material may be further processed by
conventional methods into composite products such as a liner for an
automobile. For example, the laminated composite material may be
trimmed and formed into a headliner, such as by a molding process.
Foam or fabric may then be applied to the headliner for aesthetic
purposes. The first, second, third, and fourth adhesives include
adhesives such as copolymers of ethylene and vinyl acetate (EVA),
copolymers of ethylene and acetic acid (EAA), acid modified
polyethylenes, copolyamides, and ethyl acrylate. The adhesives may
be the same or different from each other, and may be in a liquid
form, a foam form, or a powdered form. Preferably the adhesives are
liquid adhesives. It should be appreciated that although the
above-described laminate process has been described in what is
believed to be the preferred embodiment, other variations and
alternatives to this process identifiable to those of skill in the
art are also considered to be within the purview of the invention.
For example, in an alternate embodiment (not shown), the laminate
composite material may be formed by sequentially depositing layers
of a scrim 440, a first adhesive layer 410, a layer of the
composite material 320, a second adhesive layer 460, a polyethylene
terephthalate core fiber layer 490, a third adhesive layer 500, a
second layer of composite material 320, and a second adhesive layer
510.
[0079] The composite material according to the present invention
forms a final product that demonstrates improved sound absorption
properties, especially at lower frequencies (such as 2000 Hz and
below). Such improved sound absorption qualities may be seen in the
examples depicted in FIGS. 7 and 8. Turning first to FIG. 7, it can
be seen that the composite material of the present invention (the
polypropylene/glass/polyethylene terephthalate composite material)
absorbed more incident sound at all frequencies compared to a
conventional composite material formed of polypropylene and glass
fibers. Thus, not only does the inventive composite material
demonstrate improved sound absorption at lower frequencies, it also
provides improved sound absorption at both mid-range and higher
frequencies. FIG. 8 depicts a graphical illustration of the normal
incidence curves of an inventive composite material formed of
polyethylene terephthalate fibers (PET) and glass fibers and a
conventional composite material formed of organic fibers and glass
fibers and no acoustical enhancement fibers. As shown in FIG. 8,
the composite material containing the polyethylene terephthalate
fibers (acoustical enhancement fibers) has a greatly improved
absorption coefficient percentage compared to a conventional
polypropylene glass composite at frequencies below approximately
4500 Hz. The increased sound absorption qualities in the lower
frequencies provided by the inventive composite material, as shown
in FIGS. 7 and 8, provides less internal compartment noise in an
automobile from sources such as from road noise, tire noise, engine
noise, and/or wind noise and, as a result, provides more comfort to
the passengers and drivers of automobiles. For example, road noise
typically occurs between approximately 30-1000 Hz, engine noises
between approximately 500-4000 Hz, tire noise between approximately
800-2000 Hz, and wind noise between approximately 2000-4000 Hz.
Further, the composite product provides the structural integrity
and stiffness needed for structural applications that conventional
composites materials available in the market today lack.
[0080] The acoustic performance of the composite material may be
altered or improved by the specific combination of fibers present
in the composite material, and can therefore be tailored to meet
the needs of a particular application. For example, the acoustic
properties desired for specific applications can be optimized by
altering the weight of the fibers, by changing the reinforcement
fibers content and/or length or diameter of the reinforcement
fibers, or by altering the fiber length and/or denier of the
acoustical enhancing fibers or organic fibers. The thickness of the
formed composite part, porosity of the formed composite part (void
content), and the air flow path may be controlled by changing the
basis weight of the organic fibers and/or glass content of the
composite material. In addition, the use of wet use chopped strand
glass in the dry-laid process as described above also contributes
to the improved sound absorption of the inventive composite
material because the composite materials formed by the dry-laid
process described herein has a higher loft (increased
porosity).
[0081] Further, the composite material provides the ability to
optimize and/or tailor the physical properties (such as stiffness
and/or strength) needed for specific applications by altering the
weight, length, and/or diameter of the reinforcement fibers and/or
organic fibers used in the composite material. In addition,
composite materials formed by the processes described herein have a
uniform or substantially uniform distribution of fibers, thereby
providing improved strength as well as improved acoustical and
thermal properties, stiffness, impact resistance, and acoustical
absorbance.
[0082] It is another advantage of the present invention that when
wet use chopped strand glass fibers are used as the reinforcing
fiber material, the glass fibers may be easily opened and fiberized
with little generation of static electricity due to the moisture
present in the glass fibers. In addition, wet use chopped strand
glass fibers are less expensive to manufacture than dry chopped
fibers because dry fibers are typically dried and packaged in
separate steps before being chopped. Therefore, the use of wet use
chopped strand glass fibers allows the products formed from the
composite material to be manufactured with lower costs.
[0083] The invention of this application has been described above
both generically and with regard to specific embodiments. Although
the invention has been set forth in what is believed to be the
preferred embodiments, a wide variety of alternatives known to
those of skill in the art can be selected within the generic
disclosure. The invention is not otherwise limited, except for the
recitation of the claims set forth below.
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